Tapping mechanism for drilling-machines.



W. T. SEARS.

MECHANISM FOR DRILLING MACHINES. APPLICATION FILED JUNE8. ms.

TAPPING Pateniod Apr. 1, 1911).

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TUBA EV Trad RANT FFI.

T. SEARS, 0F BROOKLYN, NEW YORK, ASSIGNOR '10 NILES-BEMENT-POND COMPANY, OF NEW Y0, N. Y., A CORPORATION OF NEW JERSEY.

TAPPING MECHANISM FOR DRILLING-MACHINES.

racemes Apr. 1, was.

Application filed June a, 1918. Serial no. asaeva.

To all whom it may concern:

Be it known that I, WILLARD T. SEARS, a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Tapping Mechanism for Drilling-Machines, of which the following is a specification. I

The object of the invention is to provide an improved tapping mechanism of the type in which the tap is alternately driven forward and backward, the forward rotation being through a greater angle than the backward rotation so that the net result is an advancing movement. In accordance with my invention I provide an electric driving motor and automatic devices whereby the motor is successively reversed to effect re-- versal of the tap in the way described.

In the accompanying. drawing I have shown the embodiment of the invention which I now deem preferable, but it will be understood that the invention can be embodied in other ways within the scope of the appended claims without departing from the spirit thereof.

Of the drawing:

' Figure 1 is a slde view of a drilling machine embodying the invention.

Fig. 2 is a fragmentary sectional view onan enlarged scale taken along the line 2+2 of Fig. 1.

Fig. '3 is a diagram of electrical connec- I tions.

The drawing shows the invention embodied in a universal radial drilling machine, but it will be understood that as concerns the type of machine there can bewide "variation. As illustrated, 1 represents the base, 2 the column and 3 the vertically adjustable arm. The column 2 is divided, having two parts between which extends the arm or a carrier member therefor. Rigidly mounted at the rear end of the arm or the carrier member is a gear casing 4 which carries an electric motor 5. Slidably mounted on the arm 3 is a saddle 6 carrying a head provided with a rotatable drill spindle 7. A driving shaft 8 extends longitudinally of the arm and serves to drive the spindle. As illustrated, the saddle 6 is adjustable longitudinally of the arm and the head is angularly adjustable on the saddle. The arm itself is angularly adjustable about the axis of the shaft 8. These various an"? justmentsare incidental to the particular type of machine illustrated, and it will be understood that they are not essential in connection with the present invention.

Suitable gearing is provided in the casing 4 for transmitting power from the motor 5 to'the shaft 8. As illustrated, there is a.

pinion 9 mounted on the drive shaft of the motor, this pinion meshing with a gear 10 loosely mounted on the shaft 8. Connected withthe gear 10 is a pinion 11 which meshes with a gear 12 on a countershaft 13. Mounted on the shaft 13 is a pinion 14 which is drive from the gear 10 to the shaft 8.

Preferably, as shown, mechanism is provided for raising and lowering the arm and the motor and associated parts by power.

llhis mechanism includes bevel gearing 17 I which operates a nut engaging a vertical screw 18. Power is supplied to the bevel gearing from the countershaft 13 through a clutch-which is operated by a lever 19.

The machine can be used for drilling in the usual way, power being transmitted either directly as described from the gear 10, or indirectly through the countershaft 13. When the machine is to be used for tapping, power will ordinarily be transmitted throggh the countershaft to provide a slower spee In accordance with the invention, I provide means whereby the tap is rotated intermittently in the forward direction to a definite or predetermined extent at each actuation. Preferably after each forward actuation the tap is rotated in the reverse directionto a lesser extent, these forward and reverse rotations being continued in succession until the tapping operation is completed. I effect the intermittent forward. rotation of the tap by starting and stopping the forward move ment of the main driving motor 5. When reverse movements also take place, as is preferable, I etfect them hy reversing the main driving motor. The mechanical and electrical devices for effecting the reversal of the motor may be varied widely, but for purposes of illustration I have shown a simple construction which is suitable forthe purpose.

Mounted on the countershaft 13 is a cam 20 having lobes 21, 21. A controller casing 22 is mounted on the to of the gear casing 4 and carries a vertically movable plunger rod 23. At the lower end of this rod is a roller 24 engaging the cam 20. Rotatably mounted in the casing 22 is a shaft 25 carrying a ratchet wheel 26. A pawl 27 is mounted at the upper end of the plunger rod 23, this pawl engaging the teeth of the ratchet wheel 26. The lobes of the cam are so proportioned with respect to the teeth of the ratchet wheel that as each lobe passes under the roller 24 the rod 23 will be moved sufliciently to turn the ratchet wheel to an angle corresponding to one tooth. It will be seen, therefore, that when the shaft 13 is rotated the ratchet wheel 26 together with the shaft 25 will be given an intermittent movement in the direction indicated by the arrow. The normal direction of rotation of the shaft 13 and of the cam is indicated by the arrow on the cam, but the rotation of the ratchet wheel and of the shaft is always in the same direction irrespective of the direction of rotation of the shaft 13 and of the cam 20.

Mounted in the casing 22 is a special electrict controller 28 which may be considered as connected between the motor and the ordinary controller which forms no part of the present invention and is not shown. The controller 28 comprises an arm 29 mounted on the shaft 25. The controller arm 29 is preferably constructed with two metallic parts which are insulated from each other and from the shaft 25, these two parts being respectively adapted to engage contact rings and segments 30, 31, 32, 33, 34 and 35. The two rings 30 and 33 are connected" respectively with the brushes of the motor 5. The

two segments 31 and 34 are connected with the positive lead and the two segments 32 and 35 are connected with the negative lead. When the arm 29 is in the position shown, the ring 30 is connected with the segment 32 and the ring 33-is connected with the segment 34. In this way current is led to the motor 5 and it will be assumed that the direction is that corresponding to the forward rotation of the tap. As the rotation of the tap continues the cam 20 will be rotated, thus operating the pawl and advancing the arm 29 in the direction of the arrow. The arm will then connect the ring 30 with the segment 31 and will connect the ring 33 with the segment 35, thus reversing the connections to the armature brushes and reversing the direction of rotation of the motor. When the motor reverses it will turn the tap in the backward direction, also turning the cam 20 in the direction opposite to that indicated. However, as before stated, the cam, although rotating backward, nevertheless continues to move the ratchet wheel in the direction of the arrow. This continued movement of the ratchet wheel causes the arm 29 to pass off from the segments 31 and 35 again engaging the segments 32 and 34. The rings 30 and 33 are again connected respectively with these segments 32 and 34, thus again connecting the motor for rotation in the forward direction. This forward rotation continues until the arm 29 again engages the segments 31 and 35, whereupon reversal again takes place. Thus the forward and reverse movements automatically follow each other in succession indefinitely.

The exact amount of forward and reverse movements at each oscillation may be varied, and I do not limit myself in this respect. For purposes of illustration, however, I have shown the parts so proportioned that the tap will be given approximately three revolutions forward and approximately one revolution backward. The ratio of the diameter of the gear 15 to that of the gear 14 is approximately 2 to 1. As suming that the spindle 7 rotates at the same speed as the shaft 8, it will be clear that the gear 14 and the shaft 13 make two revolutions for each revolution of the spindle. Two revolutions of the shaft 13 and of the cam 20 cause four movements of the pawl 27. The ratchet wheel 26 has sixteen teeth and thus the ratchet wheel is moved through one-fourth of a revolutionfor each rotation of the spindle 7 The segments 31 and 35 extend through approximately 90 and the segments 32 and 34 extend through approximately 270. As illustrated in Fig. 3, the arm 29 is about to move to the position for connecting the motor for reverse rotation. One backward revolution of the spindle or four movements of the pawl 27 will bringthe arm 29 to positions near the ends of the segments 31 and 35 so that the next movement will connect the motor for normal forward rotation. Then three forward revolutions of the s indle or twelve movements of the pawl 2 will bring the arm 28 back to'the position shown in Fig. 3 and ready to again connect the motor for reverse rotation. It will be understood that when the motor is turning in the reverse direction the cam 20 is rotating in the direction opposite to that shown, but this has no effect on the direction of movement of the ratchet wheel and of the controller arm. By changing the number of teeth on the ratchet wheel or by changing the number of lobes 0n the cam. o by changing the relative lengths of the segments of the controller, the extent and ratio of forward and backward movements can be changed as desired.

In order that the mechanism may be thrown out of operation when not needed, a pin 36 is carried by the rod 23, this pin being adapted to .be engaged by a finger 37 adapted to be moved by a hand lever 38. By means of a detent 39 the lever 38 can be locked in its lower position thus permitting the roller 24 to engage the cam, or can be locked in its upper position with the finger 37 engaging the pin 36 so as to hold the roller 24 out of engagement with the cam.

What I claim is:

1. In a machine of the class described, the combination of a tap driving spindle, an electric spindle driving motor, and automatic controlling mechanism for causing the motor to drive the spindle intermittently.

2. In a machine of the class described, the combination of a tap driving spindle, an electric spindle drivin motor, and automatic controlling mec anism for successively reversing the motor to cause it to drive the spindle alternately forward and backward, the forward rotations exceeding the backward rotations.

3.,In a machine of the class described, the combination of a tap driving spindle, an electric spindle driving motor, and automatic controlling mechanism for successively reversing the motor to cause it to drive the spindle alternately forward to a predespindle alternately forward to a predetermined extent and backward to a lesser extent, and means for rendering the reversing mechanism inoperative.

5. In a machine of the class described, the combination of a tap driving spindle, an electric spindle driving motor, a motor reversing mechanism comprising a rotatable element, and motor operated means for turning the said element always in the same direction irrespective of the direction of rotation of the motor, whereby the reversing mechanism serves to successively reverse the motor to cause it to drive the spindle alternately forward to a predetermined extent and backward to a lesser extent.

In testimony whereof I hereto aflix my signature.

WILLARD T. SEARS. 

